On the intrinsic width of the chromoelectric flux tube in finite temperature LGTs

We propose three different lattice operators to measure the intrinsic width xi_I of the chromoelectric flux tube in pure lattice gauge theories. In order to test these proposals we evaluate them for SU(2) and Ising LGTs in (2+1) dimensions in the vicinity of the deconfinement transition. Using dimensional reduction, we could perform the calculation in the effective 2d spin model using standard S-matrix techniques. We consistently found the same result for the three lattice operators. This result can be expressed in terms of the finite temperature string tension as follows xi_I=frac{T}{2sigma(T)} and implies that the intrinsic width of the flux tube diverges as the deconfinement transition is approached.